Non-disruptive file system element reconfiguration on disk expansion

ABSTRACT

An apparatus is operable with a host and a data storage component for controlling expansion of storage, and comprises: an allocating component responsive to a user input for allocating an expanded target storage space to a file system element to thereby make an expanded file system element; a file system metadata component for maintaining file system metadata including metadata for said expanded file system element; a file system I/O component responsive to said file system metadata component for controlling file system I/O between said host and said storage component; and a synchronizing component responsive to said file system metadata component for synchronizing data between a source storage space and said expanded target storage space; wherein said file system I/O component is operable to use said file system metadata component to access said expanded file system element prior to completion of action of said synchronizing component.

FIELD OF THE INVENTION

The present invention relates to technology for controlling data storagesystems, and more particularly for controlling the non-disruptiveexpansion of file systems, or of elements within file systems, whenadditional space is provided in a storage system.

BACKGROUND OF THE INVENTION

Data storage systems store customer data in file systems, which havetheir physical embodiment in storage on, for example, disk, tape, or inmemory. The present invention relates to such storage systems, which maycomprise disk storage, such as computer hard disks. It will be clear toone of ordinary skill in the art, however, that other storage devices,including, but not limited to, tape and flash memory devices, may alsobe included in such a system.

When desktop users run out of space on their hard disks, they want more.It is not always an option to just add a second hard disk in the longterm, so the original hard disk must be replaced with a larger one.Doing so requires the operating system to be reinstalled as well as allof the user's existing data to be copied across. This typically requiresdowntime on the part of the user's computer—it can often take the bestpart of a day to perform all of the necessary work to do this migration.In this context ‘downtime’ refers to both the time the computer isrequired to be powered down (to physically add the second disk) and thetime the users are unable to perform their usual work because data isbeing moved, or because software programs and the like are beingreinstalled.

One option is to use software RAID to mirror the data of the originaldisk to the new disk (RAID 1). However this has the limitation that itprovides an exact mirror of the original disk, and so the additionalspace cannot be added to the existing file systems until the disks aresynchronised and the RAID relationship has been removed.

It is well known in the enterprise-level systems art to provide meansfor migrating data, as such, from one storage medium to another. Thesecond medium may be larger, providing extra space which can later beused by file systems or partitions. In some cases, such a migration maybe arranged to minimise disruption and downtime of large commercial dataprocessing systems. Examples are disclosed in, for example, U.S. Pat.No. 6,832,289, U.S. Pat. No. 5,835,954 and U.S. Pat. No. 6,230,239. Noneof these, however, discloses or contemplates any provision for theallocation of the newly-acquired expanded storage space to partitions orfile systems until after completion of the migration.

A product such as PartitionMagic™ (PartitionMagic is a trademark ofSymantec Corporation) allows users to manage their partitions and disks.However, this management activity cannot be done as a background task,and so a large amount of downtime is still required.

In the light of the problems detailed above, it would be highlydesirable to have a technological means for permitting a user to controlthe non-disruptive expansion and space allocation of file systems, or ofelements within file systems, when additional space is provided in astorage system.

SUMMARY OF THE INVENTION

The present invention accordingly provides, in a first aspect, anapparatus operable with a host and a data storage component forcontrolling expansion of storage, comprising: an allocating componentresponsive to a user input for allocating an expanded target storagespace to a file system element to thereby make an expanded file systemelement; a file system metadata component for maintaining file systemmetadata including metadata for said expanded file system element; afile system I/O component responsive to said file system metadatacomponent for controlling file system I/O between said host and saidstorage component; and a synchronizing component responsive to said filesystem metadata component for synchronizing data between a sourcestorage space and said expanded target storage space; wherein said filesystem I/O component is operable to use said file system metadatacomponent to access said expanded file system element prior tocompletion of action of said synchronizing component.

Preferably, said file system element is a file system hierarchy.

Preferably, said target storage space comprises a partition.

Preferably, said host comprises a personal computer.

Preferably, said data storage component comprises a hard disk.

Preferably, said file system metadata component comprises a bitmap.

Preferably, said file system metadata component is stored in reservedstorage.

Preferably, said synchronizing component is operable as a backgroundprocessing component.

Preferably, said synchronizing component is operable at a selectablepriority of operation.

In a second aspect, there is provided a method operable in a system witha host and a data storage component for controlling expansion ofstorage, comprising the steps of: allocating, responsive to a userinput, an expanded target storage space to a file system element tothereby make an expanded file system element; maintaining file systemmetadata including metadata for said expanded file system element;responsive to said file system metadata, controlling file system I/Obetween said host and said storage component; and responsive to saidfile system metadata component, synchronizing data between a sourcestorage space and said expanded target storage space; whereincontrolling said file system I/O comprises using said file systemmetadata to access said expanded file system element prior to completionsaid step of synchronizing data.

Preferably, said file system element is a file system hierarchy.

Preferably, said target storage space comprises a partition.

Preferably, said host comprises a personal computer.

Preferably, said data storage component comprises a hard disk.

Preferably, said file system metadata comprises a bitmap.

Preferably, said file system metadata is stored in reserved storage.

Preferably, said step of synchronizing component is operable as abackground process.

Preferably, said step of synchronizing is operable at a selectablepriority of operation.

In a third aspect, there is provided a data carrier having functionaldata thereon, said functional data comprising functional computer datastructures to, when loaded into a computer system and operated uponthereby, enable said computer system to perform all the steps of amethod according to the second aspect.

In a fourth aspect, there is provided a computer program comprisingcomputer program code to, when loaded into a computer system andexecuted thereon, cause said computer system to perform all the steps ofa method according to the second aspect.

Preferred embodiments of the invention thus contemplate, in theirbroadest aspect, a technical framework for permitting a user to controlthe non-disruptive expansion and space allocation of file systems, or ofelements within file systems, when additional space is provided in astorage system.

A preferred embodiment of the invention thus provides a method by whicha hard disk and the file systems on it can be mirrored to a second driveand by which the extra space of the second drive, allocated according tothe user's preferences, can be made available for use within those filesystems immediately.

The mirroring action may occur as a background computer operation, andso requires minimal downtime of the computer.

The additional space may be made available on the second drive beforethe mirroring is complete.

Once the mirroring is complete, the original disk may be taken out ofuse, and may be removed at the user's discretion.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the present invention will now be described,by way of example only, with reference to the accompanying drawingfigures, in which:

FIG. 1 shows in schematic form an arrangement of apparatus in accordancewith a preferred embodiment of the present invention.

FIG. 2 shows in flowchart form one method or one logic arrangement bywhich a method of operation according to a preferred embodiment of thepresent invention may be implemented.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows in schematic form an exemplary arrangement of apparatus inaccordance with one preferred embodiment of the present invention.

In a preferred embodiment of the present invention in the form of anarrangement of apparatus, as shown in FIG. 1, there is provided amigrator 100, operatively connected to a user I/O component 102, and toa storage component 112, comprising storage devices 114, 116. The systemof the preferred embodiment is positioned at a level between theoperating system and the disks and so is able to intercept the I/Operformed to the disks.

Migrator 100 comprises an allocator 104, operable to accept userrequests from user I/O component 102 for allocation of space to filesystems or file system elements. Allocator 104 provides a configurationinterface to the user to choose how the migration should be done.

Migrator 100 further comprises a file system metadata component 106 formaintaining metadata descriptive of the state (for example, a bitmapshowing whether a data item has been copied or not yet copied) of anyfile systems and file system elements that are subject to migrationusing the preferred embodiment of the present invention.

Migrator 100 also comprises a synchronizer component 108 forsynchronizing the data between the source storage device, in theexample, storage device 114 and the target storage device, in theexample, storage device 116, based on the data supplied by file systemmetadata component 106. Information from the file system metadatacomponent 106 and synchronizer component 108 is used to control theactivities of file system I/O component 110, which performs I/Oactivities to the storage devices 114, 116 in the storage component 112.

The basic flow for the migration process is broadly as follows:

1. A user decides to migrate to a larger disk.

2. The larger disk is connected to the computer; this may require themachine to be shut down.

3. The user is then able to select how the migration should occur foreach of the file systems on the disk. The main user-selectable option ishow the additional space of the new disk should be distributed acrossthe existing file systems. A further option may be the rate at which thesynchronisation should occur in the background. Further refinements andadditions to these basic options will be clear to one of ordinary skillin the programming art.

In the example shown in FIG. 1, file system A is to be migrated fromstorage device 114 to storage device 116 with the additional space Bmade available so the file system on storage device 116 will comprisethe larger space A′+B.

Once the user has chosen how the migrations should occur, he or she canthen initiate the migration. Once any expanded space allocations havebeen made and migration has been initiated, the file system metadataheld by file system metadata component 106 is modified as appropriate(by expansion, for example) for the particular file system so that thefile system can determine that additional space has been made availablefor particular file system elements. From the user's perspective, thefile system is now of the larger size and is completely available foruse.

Invisibly to the user, synchronizer component 108 of the migrator 100 isactively synchronising the contents of the file system as stored onstorage devices 114 and 116. This is done as follows:

1. Any I/O (read or write) that is addressed to a block in the B portionof the file system is sent to storage device 116 by the file system I/Ocomponent 110.

2. Any read that is addressed to a block in the A portion of the filesystem is sent to storage device 114 by the file system I/O component110 to be satisfied from A.

3. Metadata (for example, a bitmap) is maintained by file systemmetadata component 106 of which blocks of A have been mirrored to A′.

4. Any write that is addressed to a block in the A portion of the filesystem is sent by the file system I/O component 110 to both the sourcestorage device 114 to be written to A and to the target storage device116 to be written to A′; it is not completed until both writes arecomplete. The bitmap is then updated by file system metadata component106 to mark this block as being in synchronization.

5. A background process under control of synchronizer component 108 runsthrough the bitmap (at a priority rate that may be specified by the userwhen setting up the migration) to copy any unsynchronized data from A toA′ by initiating writes by file system I/O component 110. The bitmap isupdated by file system metadata component 106 to record the progress ofthis synchronization.

6. Once the bitmap processing under control of synchronizer component108 is complete the system determines that A and A′ are nowsynchronised. The storage device containing A is now no longer required,and so the system can start solely using the new storage device.

As will be clear to one of ordinary skill in the art, if the storagedevice that is to be migrated is the system's boot device, the MasterBoot Record will also have to be copied to the new device and alteredwhere necessary to reflect the expanded partitions, in addition to thepreviously-described copying of the file systems on the storage device.

7. The user is prompted that the old disk is no longer actively beingused and so it can be removed.

The preferred embodiment of the present invention in the form of anapparatus thus advantageously provides for the non-disruptive expansionof file systems, or of elements within file systems, when additionalspace is provided in a storage system.

The bitmap that is used to track the migration progress may be stored onthe new disk in a reserved area not available to the user. By keepingthis information on disk in this way, the user is able to shut down thecomputer without losing track of the migration progress, which can thusbe resumed at a later time.

Turning now to FIG. 2, there is shown in flowchart form one method orone logic arrangement in which a method of operation according to apreferred embodiment of the present invention may be implemented.

In FIG. 2, following START step 200, at step 202 a target storage deviceis activated. At step 204, user input is accepted to determine theallocations of target storage space to file systems (or, in analternative that will be clear to one of ordinary skill in the art, offile system elements).

At step 206, file system metadata is modified to reflect the allocationsof target storage space to file systems resulting from step 204. At step208, I/O-initiated synchronization is started, and file system I/O isenabled at step 210. At step 212, background synchronization is enabledand continues in parallel with I/O-initiated synchronization until thefile system metadata indicates that synchronization is completed at step214. At step 216, the source storage device is “released” and may betaken offline, as it is no longer needed. The process completes at ENDstep 218.

The preferred embodiment of the present invention in the form of amethod or logic arrangement thus advantageously provides for thenon-disruptive expansion of file systems, or of elements within filesystems, when additional space is provided in a storage system.

It will be clear to one of ordinary skill in the art that all or part ofthe method of the preferred embodiments of the present invention maysuitably and usefully be embodied in a logic apparatus, or a pluralityof logic apparatus, comprising logic elements arranged to perform thesteps of the method and that such logic elements may comprise hardwarecomponents, firmware components or a combination thereof.

It will be equally clear to one of skill in the art that all or part ofa logic arrangement according to the preferred embodiments of thepresent invention may suitably be embodied in a logic apparatuscomprising logic elements to perform the steps of the method, and thatsuch logic elements may comprise components such as logic gates in, forexample a programmable logic array or application-specific integratedcircuit. Such a logic arrangement may further be embodied in enablingelements for temporarily or permanently establishing logic structures insuch an array or circuit using, for example, a virtual hardwaredescriptor language, which may be stored and transmitted using fixed ortransmittable carrier media.

It will be appreciated that the method and arrangement described abovemay also suitably be carried out fully or partially in software runningon one or more processors (not shown in the figures), and that thesoftware may be provided in the form of one or more computer programelements carried on any suitable data-carrier (also not shown in thefigures) such as a magnetic or optical disk or the like. Channels forthe transmission of data may likewise comprise storage media of alldescriptions as well as signal-carrying media, such as wired or wirelesssignal-carrying media.

The present invention may further suitably be embodied as a computerprogram product for use with a computer system. Such an implementationmay comprise a series of computer-readable instructions either fixed ona tangible medium, such as a computer readable medium, for example,diskette, CD-ROM, ROM, or hard disk, or transmittable to a computersystem, via a modem or other interface device, over either a tangiblemedium, including but not limited to optical or analogue communicationslines, or intangibly using wireless techniques, including but notlimited to microwave, infrared or other transmission techniques. Theseries of computer readable instructions embodies all or part of thefunctionality previously described herein.

Those skilled in the art will appreciate that such computer readableinstructions can be written in a number of programming languages for usewith many computer architectures or operating systems. Further, suchinstructions may be stored using any memory technology, present orfuture, including but not limited to, semiconductor, magnetic, oroptical, or transmitted using any communications technology, present orfuture, including but not limited to optical, infrared, or microwave. Itis contemplated that such a computer program product may be distributedas a removable medium with accompanying printed or electronicdocumentation, for example, shrink-wrapped software, pre-loaded with acomputer system, for example, on a system ROM or fixed disk, ordistributed from a server or electronic bulletin board over a network,for example, the Internet or World Wide Web.

In an alternative, the preferred embodiment of the present invention maybe realized in the form of computer implemented method of deploying aservice comprising steps of deploying computer program code operable to,when deployed into a computer infrastructure and executed thereon, causesaid computer system to perform all the steps of the described method.

It will be clear to one skilled in the art that many improvements andmodifications can be made to the foregoing exemplary embodiment withoutdeparting from the scope of the present invention.

1. An apparatus operable with a host and a data storage component,comprising: an allocating component responsive to a user input toallocate an expanded target storage space to a file system element tomake an expanded file system element; a file system metadata componentto maintain file system metadata including metadata for said expandedfile system element; a file system I/O component responsive to said filesystem metadata component to control file system I/O between said hostand said storage component; and a synchronizing component responsive tosaid file system metadata component to synchronize data between a sourcestorage space and said expanded target storage space, wherein said filesystem I/O component is operable to use said file system metadatacomponent to access said expanded file system element prior tocompletion of action of said synchronizing component.
 2. The apparatusof claim 1, wherein said file system element is a file system hierarchy.3. The apparatus of claim 1, wherein said synchronizing component isoperable as a background processing component.
 4. The apparatus of claim3, wherein said synchronizing component is operable at a selectablepriority of operation.
 5. A method, comprising: allocating, responsiveto a user input, an expanded target storage space to a file systemelement to make an expanded file system element; maintaining file systemmetadata including metadata for said expanded file system element;responsive to said file system metadata, controlling file system I/Obetween a host and a storage component; and responsive to said filesystem metadata, synchronizing data between a source storage space andsaid expanded target storage space, wherein controlling said file systemI/O comprises using said file system metadata to access said expandedfile system element prior to completion of the synchronizing of thedata.
 6. The method of claim 5, wherein said file system element is afile system hierarchy.
 7. The method of claim 5, wherein thesynchronizing is performed via a background process.
 8. The method ofclaim 7, wherein the synchronizing is operable at a selectable priorityof operation.
 9. (canceled)
 10. A computer readable medium having storedtherein computer program code, wherein the computer program code whenloaded into a computer system and executed thereon, cause said computersystem to perform: allocating, responsive to a user input, an expandedtarget storage space to a file system element to make an expanded filesystem element; maintaining file system metadata including metadata forsaid expanded file system element; responsive to said file systemmetadata, controlling file system I/O between a host and a storagecomponent; and responsive to said file system metadata, synchronizingdata between a source storage space and said expanded target storagespace, wherein controlling said file system I/O comprises using saidfile system metadata to access said expanded file system element priorto completion of the synchronizing of the data.
 11. The computerreadable medium of claim 10, wherein said file system element is a filesystem hierarchy.
 12. The computer readable medium of claim 11, whereinthe synchronizing is performed via a background process.
 13. Thecomputer readable medium of claim 10, wherein the synchronizing isperformed via a background process.
 14. The computer readable medium ofclaim 13, wherein the synchronizing is operable at a selectable priorityof operation.
 15. The apparatus of claim 2, wherein said synchronizingcomponent is operable as a background processing component.
 16. Themethod of claim 6, wherein the synchronizing is performed via abackground process.